1. Field of the Invention
The present invention relates to an electronic part-mounted substrate on which a heat-generating electronic part such as IC is provided, and a liquid-jetting head such as an ink-jet head.
2. Description of the Related Art
The electronic equipment such as mobile phones and personal computers includes a large number of electronic parts such as IC's (integrated circuits), resistors, and capacitors mounted on the surface of the substrate or the circuit board. Those widely used as the substrate on which the electronic parts as described above are mounted include those obtained by impregnating the surface of the glass cloth with the epoxy resin (glass epoxy substrate). When any heat-generating electronic part such as IC is provided on the substrate, it is necessary that the heat, which is generated from the electronic part, is reliably dissipated to the outside in order to prevent the electronic part itself or any part disposed therearound from being destroyed by the heat generated from the electronic part. However, in recent years, there is such a tendency that a large number of electronic parts are arranged and clustered in a narrow area on the substrate in order to miniaturize the electronic equipment. Therefore, it is more difficult to dissipate the heat generated from the heat-generating electronic part to the outside. In view of the above, a variety of electronic apparatuses have been suggested, which make it possible to efficiently dissipate the heat generated from the electronic part.
For example, an electronic apparatus described in Japanese Patent Application Laid-open No. 2003-76445 (FIG. 2) is provided with a thermal conductor constructed of a metal plate or the like which makes contact with the surface of a heat-generating electronic part such as CPU, a cooling fan which is installed in the vicinity of the thermal conductor, and a heat exchange section which transmits the heat transmitted from the electronic part to the thermal conductor to a heat transfer medium. The heat, which is transmitted from the electronic part to the thermal conductor, is transmitted at the heat exchange section to the heat transfer medium (fluid). The heat is dissipated to the outside via the heat transfer medium.
However, even when the apparatus is constructed so that the heat dissipation is facilitated from the surface of the electronic part as in the electronic apparatus described in Japanese Patent Application Laid-open No. 2003-76445, the heat is scarcely dissipated from the substrate, because the substrate, on which the electronic part is mounted, is composed of a material such as epoxy resin which has a low coefficient of thermal conductivity. Therefore, it is feared that the heat, which is generated by the electronic part, is not dissipated sufficiently, and the temperature of the electronic part is excessively increased.